This invention relates to an apparatus for detecting the passage of multiple superposed sheets along a feed path. The invention has application, for example, to an apparatus for detecting the passage of superposed currency notes in a cash dispensing mechanism of an automated teller machine (ATM).
In a cash dispensing mechanism, it is important to provide a simple and reliable means for detecting when a currency note has become superposed on another in a path of travel from a currency supply means to a note exit slot, since such superpositioning may produce an undesirable result such as the dispensing of an excessive amount of money. For convenience, two or more sheets or notes which have become disposed in a superposed relationship will hereinafter be referred to as a multiple sheet or multiple note.
One known type of apparatus for detecting the passage of multiple notes along a feed path employs a pair of gauging rollers between which notes are fed in operation. In the event of a multiple note (or an excess thickness note) passing between the rollers, the axis of one of the rollers is displaced by an amount such that a note rejecting means is actuated, actuation of the rejecting means causing the notes or note to be diverted into a reject hopper. A problem experienced with known apparatuses of this type is that such apparatus may not distinguish between multiple notes and a single note having a localized increase in thickness, brought about for example by a crease or fold in the note or by the attachment thereto of extraneous matter such as adhesive tape. As a result, there is a tendency for such apparatus to reject an excessive number of notes. The use of such apparatus in a cash dispensing mechanism of an ATM would tend to increase maintenance costs, since the rejection of an excessive number of notes would decrease the period of time between successive replenishments of the machine with currency notes.
An apparatus which is intended to overcome the aforementioned problem is disclosed for example in U.K. Patent Application No. 2001038A. This known apparatus employs a thickness sensor arranged to gauge a portion of a currency note and to generate a digital signal in response to note thickness, for example a logic 1 signal in response to a multiple note thickness and a logic 0 signal in response to a single note thickness. The digital output of the thickness sensor is applied to an integrator circuit which integrates this output over substantially the entire length of the gauged portion of the note. The output of the integrator circuit is compared with a reference signal in order to determine if the gauged note is a multiple note or a single note. Although this known apparatus is able to distinguish between a multiple note or a single note having localized areas of increased thickness that might be caused by dirt or creases, the apparatus is not able to determine the number of notes being sensed at any instant. For example, the apparatus is not able to distinguish between two superposed notes and three superposed notes.
According to the invention there is provided an apparatus for detecting the passage of superposed sheets along a feed path, comprising a frame for said apparatus first and second cooperating rollers, said first roller being secured on a shaft mounted in said frame and having a fixed axis of rotation, and the diameter of one of said rollers being equal to, or a multiple of, the diameter of the other roller; means for feeding sheets along said feed path between said rollers; means for mounting said second roller so that its axis is movable relative to that of said first roller and so that it is biased towards said first roller to enable said second roller to be displaced away from said first roller in response to a single or multiple sheet passing between said first and second rollers, said means for mounting including flexible anchor means mounted on said frame; a pivotally mounted rod substantially fixed in said anchor means at one end, on which rod said second roller is rotatably mounted; a support structure on said frame; and a connector member pivotally mounted on said support structure, coupled to an end of said rod remote from said one end; voltage generating means associated with said second roller and arranged to produce an output voltage which varies linearly with movement of the axis of said second roller toward or away from the axis of said first roller, said connector member being connected to said voltage generating means, whereby the passage of a single or multiple note between said first and second rollers brings about pivotal movement of said connector member, said pivotal movement causing a variation in the output voltage of said voltage generating means; integrator means coupled to said voltage generating means for integrating voltage values, to which said output voltage is applied in operation; data storage means coupled to said integrator means for storing values representing voltages; control means for causing said integrator means to store in said data storage means a first value representing the output voltage of said voltage generating means integrated over one complete revolution of said one of said rollers when no sheet is passing between said first and second rollers, and a second, value representing the output voltage of said generating means integrated over one complete revolution of said one of said rollers during which a single or multiple sheet passes between said first and second rollers; and data processing means coupled to said data storage means for subtracting said first value from said second value to produce a third value on the basis of which a determination is made of the number of sheets corresponding to said second value.
It should be understood that the ability of an apparatus in accordance with the invention to determine the number of sheets making up a detected multiple sheet is of importance, since when it is used in a cash dispensing mechanism, for example, it enables a multiple note to be counted as the appropriate number of notes and then dispensed to a customer. Alternatively, if a detected multiple note is diverted to a reject bin, the apparatus of the present invention would enable a record to be kept of the total number of notes which have been deposited in the reject bin.
It is accordingly an object of the present invention to provide an apparatus for detecting a multiple note, which apparatus is of simple construction and can determine the actual number of notes making up a detected multiple note.
With this and other objects, which will become apparent from the following description, in view, the invention includes certain novel features of construction and combinations of parts, a preferred form or embodiment of which is hereinafter described with reference to the drawings which accompany and form a part of this specification.